The present invention relates to indoor and outdoor advertising banners and more particularly relates to banners manufactured from nonwoven polyolefin film-fibril sheets.
Bonded nonwoven sheets of polyolefin film-fibrils of the type disclosed in Steuber, U.S. Pat. No. 3,169,899 are used for banners such as those designed for indoor and outdoor advertising. A commercial polyethylene film-fibril sheet product sold by E. I. du Pont de Nemours and Co. under the trademark TYVEK.RTM. is particularly suitable for such applications. TYVEK.RTM. bonded nonwoven polyethylene film-fibril sheets are lightweight and have outstanding mechanical properties while also having good tolerance to ordinary weather conditions.
Known banners manufactured from bonded nonwoven polyethylene film-fibril sheets, however, have some deficiencies. To make a typical banner having a width substantially greater than its height, the top and bottom of a sheet panel are folded over, a rope is placed inside the fold, and the folded edge is stitched to form a seam. In addition, each end of a typical banner is also seamed. The banner is then hung by suspending it between the two ropes. Since the ropes stretch with time, the banner eventually wrinkles, detracting from its appearance. More importantly, the slack in the ropes and the banner provides an opportunity for wind to catch the banner, whipping it back and forth. This flexing can weaken the fabric, cause the lettering to flake off, and eventually cause the seams to weaken and come apart. Although the film-fibril sheet is strong, the needle holes through the sheet can initiate a tear which can propagate and result in the destruction of the banner.
An alternative suspension method for hanging banners is to use rings or grommets in each corner, and support the banner by ropes attached to the corners. This technique works for small banners which are not greatly affected by wind. For larger, outdoor banners, the grommets typically tear out of the corners since a typical brass grommet does not grip the sheet well and does not grip a sufficient area and thus all of the stress from the suspension system is concentrated on the hole. Ultimately, this leads to destruction or even complete loss of the banner.
An additional failing of current banners is the difficulty of obtaining good printing on the polyolefin surface. Water-based inks do not wet the surface well, and thus may not give sharp printing. Solvent-based inks may cause puckering due to retraction of the oriented film-fibrils, which occurs when contacted by certain solvents. Stick-on vinyl letters used instead of inks can also cause puckering since they often contain solvents or plasticizers as components of the adhesive.